With projections of 9.5 billion people by 2050, humankind faces the challenge of feeding modern diets to additional mouths while using the same amounts of water, fertilizer and arable land as today.

Cornell researchers have taken a leap toward meeting those needs by discovering a gene that could lead to new varieties of staple crops with 50 percent higher yields.

The gene, called Scarecrow, is the first discovered to control a special leaf structure, known as Kranz anatomy, which leads to more efficient photosynthesis. Plants photosynthesize using one of two methods: C3, a less efficient, ancient method found in most plants, including wheat and rice; and C4, a more efficient adaptation employed by grasses, maize, sorghum and sugarcane that is better suited to drought, intense sunlight, heat and low nitrogen.

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The finding "provides a clue as to how this whole anatomical key is regulated," said Turgeon. "There's still a lot to be learned, but now the barn door is open and you are going to see people working on this Scarecrow pathway." The promise of transferring C4 mechanisms into C3 plants has been fervently pursued and funded on a global scale for decades, he added.

If C4 photosynthesis is successfully transferred to C3 plants through genetic engineering, farmers could grow wheat and rice in hotter, dryer environments with less fertilizer, while possibly increasing yields by half, the researchers said.

C3 photosynthesis originated at a time in Earth's history when the atmosphere had a high proportion of carbon dioxide. C4 plants have independently evolved from C3 plants some 60 times at different times and places. ....

Without reading the research publication itself, it is hard to know if the 'hype' is real or not.

This article only said in the experiment maize with the mutant Scarecrow genes grew with problems in the roots, and "the leaves of Scarecrow mutants had abnormal and proliferated bundle sheath cells and irregular veins."

The basic science is credible: for lurkers, C3 and C4 metabolic pathways refer to the number of carbons stored in molecules which are intermediaries to the creation of sugar (and, thus, starch) from carbon-dioxide. C4 plants can absorb carbon dioxide at night, for photosynthesis during the day. This is important because the same pores (”stoma”) used to gain carbon dioxide allow water to escape, so absorbing carbon at night means opening stomata (pl. of stoma) only during the cooler, moister times.

Of course, simply tinkering with the carbon-fixing metabolic pathway doesn’t turn a day-breathing plant into a night-breathing one. There are many anatomical adaptations to go with it, since you can’t exactly tell a plant, “Hey, it’s day time, but hold your breath; you can do all that breathing at night because I just genetically engineered a new metabolic process for you!”

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